Noise muffled air ejector



United States Patent [72] Inventor su hi-J. GM 1,122,733 12/1914 Goodfellow 181/60UX 5846M Road, North Royalton, Ohio 2,681,255 6/1954 Downey 239/552 [2" A l N s FOREIGN PATENTS PP 0 {22] PM 1,773 1871 Great Bntam 181/60 [45] Patented Nav. 3, 1970 Primary Examiner-Robert S. Ward, Jr.

AttorneyEly, Golrick and Flynn [54] NOISE MUIILED All HECTOR lai- 2 Dra u c m ABSTRACT: Noise muffler for air-ejectors comprising a plug [52] US. CL 181/36, for h outlet of an air pamzcway having three or more sub 181/56 81160339552 stantially equally spaced tapered openings whose axes are [51] II. Cl. F01! 1/00, n to he is the outlet By hereby "which" the fl Bosh 1/14 of air to approximately one-third or less (up to approximately [50] 7 Field OI Search 181/35, 36, n eilhth) of he quanmy discharged in the abnnce f the 46; 239/552 plug, the noise of the ejector is significantly reduced without significant reduction of thrust efficiency and increased effl- [56] cm ciency of air consumption. Optimumefficiency is obtained by UNITED STATES PATENTS a diffusion screen located adjacent the inlets to the tapered 748,364 12/1903 Gordon; 239/552X openings.

NOISE MUFFLED AIR EJECTOR The invention relates to an improvement in devices for pneumatic material handling and conveying, such as, specifically, ejecting parts and products from forming means. Sheet metal stampings ejected by sharp blasts of air from the stamping dies in which they are formed, rather than by means of ejection pins or similar mechanical means, are common examples of products thus handled pneumatically.

l-ieretofore, such a typical air ejector has comprised a metal tube which directs a sudden blast of air at the edge of a stamping when the forming dies are opened, whereby the part is at least lifted or shiftedso that it can be readily removed by the operator if it is not, in fact, literally blown out of the way to clear the die for the next operation. Or, in the case of heavy metal parts particularly, the die itself may be provided with openings in the die surface which are the orifices of passageways in the die. The above-described ejector tubes or the passageways in the die are connected to a quick-opening valve which, in turn, is connected to a source of high pressure air; the valve operates in conjunction with the stamping machine so that, at the proper time in the stamping cycle, the part is ejected by the blast of air.

Heretofore, a very serious problem and drawback of such air ejectors has been the noise which they create and the consequent strain on the operations created by the sudden blast of air-usually very shrill. Particularly when a battery of such machines equipped with air ejectors is employed, the noise, or, more particularly, the sudden change in noise level as the ejectors in the several machines operate at different intervals, creates nearly intolerable working conditions.

Devices made according to this invention accomplish the seemingly contradictory objectives of maintaining adequate thrust efficiency and simultaneously substantially reducing the shrill noise that heretofore appeared to be an inherent fault of effective air ejectors. This object is accomplished without significant loss of thrust whilesubstantially reducing the actual consumption of compressed air by any given ejector. Further, devices made according to this invention are relatively small and compact, little larger than the conventional tube to which they may be attached; such compactness is a necessity, since frequently there is limited space available between opened dies for the air ejector.

The means by which these objects and advantages are obtained is shown by the following drawings:

FIG. 1 is a side elevation partly in section of a device, in its preferred form, made according to this invention.

FIG. 2 is an end view of the device shown in FIG. 1.

As shown in FIG. 1, the device comprises a casing or sleeve 11 having at one end a fitting 12 whereby the device may be connected to the tube or pipe by which highly compressed air is supplied to the device 10. In this case the fitting 12 is provided with threads 13 for connection to the air-supply tube or pipe; the fitting 12 is provided with a suitable head 14 having nut faces for connecting and disconnecting the device to such air supply.

The other, i.e., discharge, end of the casing is counter-bored to receive a relatively coarse diffusing screen 15 and a plug 20, the depth of the counter-bore being slightly greater than the length of the screen and plug so as to allow, in this instance, a slight end portion of the casing to be spun over, thereby providing a simple means ofrctaining the plug and screen in the discharge end of the casing 11.

The plug is provided with a discharge face 21 which is traverse to the bore of the casing and conically dished inlet face 22, the angle of an element of the cone in this dished portion with respect to its axis being 70 in the embodiment shown, this cone angle may vary from one in the order of 60' up to 85, or the inlet'surface may be transverse to the air flow, in which case a small spacer ring may be inserted between the plug and the diffusing screen to provide the preferable space between the screen and the entrance orifices of the nozzles 25, to be described below.

As shown in FIGS. 1 and 2, the plug 20 is drilled with a plurality of tapered holes to provide the nozzles 25. The inlet oritices of the nozzles are preferably substantially tangent to and equally spaced about the circumference of a circle concentric with the axis of the bore of the casing 10. The axis of the nozzles are parallel to the axis of the plug and the taper of thenozzles is determined by the number of nozzles desired and the axial length of the plug, which, empirically, appears to be upwardly for a minimum of about one-fifth of the diameter of the bore of the inlet to the casing. in the embodiment shown, the length of the plug is approximately equal to the bore of the fitting 12 which constitutes the inlet to the casing; greater lengths of the plug produce no significant improvements and plugs which have a length less than one-third of the diameter generally do not appear to allow for the economical machining of nozzles which can produce jets having the desired effect. The number of nozzles may vary upwardly from three (five, as illustrated in the drawings appears preferable) to control the rate of discharge of air through the plug as compared with that of the unrestricted flow through the device if the plug 20 and diffusing screen 15 were removed. In the preferred embodiment disclosed the restricted flow effected by the plug is approximately one-fifth of that which could result in the absence of the plug and screen, although the restricted air flow may range between approximately onethird to one-seventh or eighth. Less restricted air flow does not affect a sufficiently adequate reduction of noise and more restricted air flow appears to provide no particularly greater reduction of noise but does reduce the thrust efficiency.

The effect of the diffuser screen and the dishing of the adjacent inlet face of the plug is not fully understood and, in deed, the screen may be 30 but the efficiency of the plug is thereby reduced; apparently the screen either reduces turbulence of the air as it enters the nozzles 25 or minimizes the channeling of the air flow by standing waves which may otherwise bulld up .at the inlet face of the plug and extend into the casing 11 away from the inlet face in opposition to the general direction of air flow.

The net effect of the restriction effected by the plug appears to be that of providing a plurality of jets of air which form an envelope of higher velocity air, which. on the one hand, has substantially equal thrust effect as unrestricted flow from the casing would have, but which, on the other hand, attenuates the noise of such unrestricted flow.

It is to be understood, of course, that this invention is not necessarily restricted to the particular embodiment shown. For example, if the dies are provided with openings for internal passageways for ejecting air, the same noise-attenuating (without material loss-of thrust) effect of this invention may be obtained by simply counter-boring the passageway outlet slightly (to provide a retaining shoulder for the diffusing screen) and then force-fitting a plug, drilled to provide the requisite nozzles into the outlet of the passageway. The term "air" as used in the claims, does not exclude use of other gases and vapors.

This invention is not limited, therefore, to the particular embodiments disclosed, but may be varied without departing from its scope as defined in the following claims.

lclaim:

1. A noise-reducing muffler for air-ejector means, said means having a passageway for air under pressure and directed at the location of an article to be moved by a blast of air, and a plug closing the outlet of said passageway and having three or more openings therethrough extendingaxially'and parallel to the axis of said passageway outlet to provide an envelope of jets of air about the projected axis of said outlet and directed toward said article.

2. A muffler as defined in claim 1 in which the axes of said openings are located at substantially equal radial distances from the axis of said plug and are substantially equally angularly spaced from each other.

3. A muffler as defined in claim 2 in which each of said openings is tapered toward a smaller diameter at its discharge end to provide a nozzle effect and increase the velocity of the air passing therethrough.

of said plug is approximately one-third or more of the diame- 'ter of said plug.

5. A muffler as defined in claim 4 including a screening member spaced from the plug openings, said member having mesh openings sufficient to allow air to pass therethrough without significant drop in air pressure across it and sufficiently small to prevent significant channelizing of air entering said plug openings.

6. A muffler as defined in claim 5 in which said screening member bears against the periphery of said plug and the sur-' face of said plug adjacent said screen is dished from the periphery toward its center to provide a spacing between said screening member and said plug openings.

7. A muffler as defined in claim 1 in which said means having a passageway for air under pressure comprises a casing receiving said plug at anouter end and means connected to the inner end of said casing for connecting said casing to a conduit for air under pressure.

8. A muffler as defined in claim 7 in which the axes of said plug openings are located at. substantially equal radial 4'; A muffler a. define d 1.; claim Sinwhieh'the axial length distances from the axis-jof said plug and are substantially 11. A muffler as defined in claim 10 including a screening member spaced from the plug openings, said member having mesh openings sufficient to allow air to pass therethrough without significant drop in air pressure across it and sufficiently small to prevent significant 'channelizing of air entering said-plug openings. 7

12. A muffler as defined in claim 11 in-which said screening member bears against the periphery of said plug and the surface of saidIplug adjacent said screen is dished from the periphery toward its center-to provide a spacing between said screening member and said plug openings. I

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,537,543 Dated November "4 1070 Inventor(5) J.

It is certified that error appears in the above-identified patent and. that said Letters Patent are hereby corrected as shown below:

Column 2,. line 31, "30" should read omitted Signed and sealed this 1st day of May 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-1050(10-69) ..A- U.. i -i i- 

